Carrier aggregation is a feature for increasing average user throughput of mobile stations by enabling the mobile station to exploit unused resources on a secondary component carrier. In the absence of carrier aggregation, the resource blocks on the two component carriers are segregated so that mobile stations assigned to a first component carrier cannot be allocated unused resources on the second component carrier. Carrier aggregation is especially beneficial if the loading of the two component carriers is unbalanced so that many of the resource blocks on the second component carrier would be unused if they cannot be assigned to mobile stations on the first component carrier. Carrier aggregation also increases the peak data rate achievable by the mobile station; however, reduced transmission power levels may be required on the mobile station to meet emissions requirements and to reduce interference in adjacent channels due to non-linear characteristics of mobile station power amplifiers. In some cases of uplink carrier aggregation, a required additional maximum power reduction (“A-MPR”) for determining uplink transmission power is large. The A-MPR allowed for uplink carrier aggregation is specified in two different ways for non-contiguous allocations and contiguous allocations.
For non-contiguous allocations (e.g., allocations with multiple clusters), the A-MPR is specified as a function of an allocation ratio A of the non-contiguous allocation. The allocation ratio is the ratio of a number of allocated resource blocks to a total number NRB_agg of aggregated resource blocks available for the uplink transmission. For contiguous allocations, the A-MPR is specified using a table lookup. A contiguous allocation is defined as an allocation which has no unallocated resource blocks between a first allocated resource block and a last allocated resource block. An allocation which spans a boundary between first and second aggregated carriers is said to be contiguous if there are no gaps except for internal guard bands between the first and second aggregated carriers. In this case, the last resource block of the first aggregated carrier and the first resource block of the second aggregated carrier are both allocated.
The A-MPR allowed for contiguous allocations is typically significantly less than is allowed for non-contiguous allocations. However, the tables defined for contiguous allocations cannot be used for allocation ratios greater than 0.5 for any subframe in which a physical uplink control channel (“PUCCH”) is transmitted (e.g., by other mobile stations) on either of the two contiguous carriers because any such allocation will be “punctured” by resource blocks for the PUCCH. Since the PUCCH is used for acknowledgement, negative acknowledgement, and channel-state information, most subframes will include a PUCCH transmission and for these subframes, and the tables for contiguous allocations cannot be used.